1. Field of the Invention
The invention concerns an arrangement for the automatic adjustment of the height of cut of a front harvesting attachment on a harvesting machine for the harvest of stalk-like plants.
2. Related Technology
Forage harvesters are used primarily for the harvest of grass, corn or other forage plants. While pick-ups that are guided at a constant height above the ground by touch contact are used in harvesting of grass, the use of corn heads or cutter heads is common practice as the front harvesting attachment for forage harvesters in the harvesting of corn or the whole plant silage of cereal crops. The height of cut of such front harvesting attachments for the cutting of stalk-like crops can be varied.
In the state of the art, the height of cut is provided as an input by the operator of the forage harvester and is controlled automatically by the control arrangement with the use of sensors and actuators. In such a way, a predetermined height of cut or a predetermined contact pressure of the front harvesting attachment is maintained. In the case of the input of the height of cut contradictory interests must be considered. On the one hand, the cut height of the front attachment of a forage harvester has a considerable effect upon the yield per unit area and the length of the remaining stubble on the field. On the other hand, it also affects the quality of the mass of forage produced where a low cut height is less desirable in the light of the optimization of the quality. Ground particles, such as sand particles, adhering to stalks (for example, stalks of corn plants) can considerably increase the wear of cutting tools on front harvesting attachments and of following machine components such as chopper arrangements. Due to cost considerations, it may not be in the interests of the operators of such forage harvesters to utilize the lowest cut height. On the other hand, plowless farming (in connection with direct sowing) is gaining considerable significance. This, in turn, demands the least possible length of stubble and, hence, the lowest cut height. Thus, the operator of the forage harvester is confronted by the problem of finding the optimum cut height associated with the immediate case.
Moreover, the harvest of high food energy silage, that is, corn with a high proportion of corn ears, the harvested crop must be cut at a relatively great height above the ground. Here, the operator must see to it that the plants are cut as close as possible underneath the corn ears themselves. A manual re-adjustment of the cut height does not, as a rule, lead to optimum results over large time intervals.
DE 102 25 098 A proposes that the cut height used in each case be detected by measurement technology and to log the cut height with a geographical reference. This, however, does not assist the operator in the selection of the appropriate cut height.
It has also been proposed that the content of various constituents. particularly the nitrogen and protein content, of a cereal crop be determined by an analysis of the crop made by means of an appropriate sensor during the harvest of the cereal crop with a combine. As a result of the analysis, the cereal crop is loaded into differing containers. EP 0 732 740 A, WO 03/029792 A and “Protein Mapping of Spring Wheat using a Mobil Near Infrared Sensor and Terrain Modeling”, Corey Grant Meier, M. Sc. Thesis, Montana State University, Bozeman, Mont., USA, April 1004, all relate to this concept. Also, an analysis of the crop material on board a forage harvester to determine the content of certain constituents is described in DE 199 22 867 A. In this reference, the results of the analysis are merely mapped.
The problem underlying the invention is seen as the need to simplify for an operator of a forage harvester the adjustment of the cut height.